Attenuating effect of bifemelane on an impairment of mealtime-associated activity rhythm in aged and MK-801-treated rats

In the present experiment, we examined the attenuating effect of bifemelane hydrochloride (BF), 4-(o-benzyl phenoxy)-N-methylbutylamine hydrochloride, on the impairment of time perception caused by daily scheduled feeding using aged and MK-801-treated rats. When feeding was restricted to a single meal at a fixed time of day (1300-1700 h) for six successive days, young rats exhibited intense locomotor activity 1-3 h before feeding time. Intense locomotor activity was observed for 1200-1700 h even on the fasting day (day 7; mealtime-associated activity). Mealtime-associated activity was impaired in 24-mo-old rats and also in N-methyl-D-aspartate receptor antagonist, MK-801-treated rats. Daily injections of bifemelane at 1700 h for six successive days significantly attenuated the impairment of mealtime-associated activity on the seventh day in a dose-dependent manner in aged rats. In addition, cotreatment of MK-801 with bifemelane blocked the MK-801-induced impairment of mealtime-associated activity. The present study suggests that bifemelane has an enhancing effect on learning and memory performance, such as spatial and temporal perception.